However, shortly after posting the picture, Alli found herself the centre of several jealous comments from fans of the band.

One fan wrote that Alli was 'living off your brothers fame', while another tweeted: 'Awwwww you're so luckyy!!!!'

But one of Alli's fans retaliated against the comment that she was just famous because of her older sibling, tweeting: '@allisimpson is a model & an actress . She can like other famous
people even if she is famous. Jelousy Is The Ugliest Trait.'

Number one fan: Alli attended a One Direction concert earlier in the week

And while she was more than satisfied
with simply posing for a happy snap with Harry, the 18-year-old has
admitted to having to fight off older women, who are much more confident
when they meet him.

'The fans sometimes get very graphic and there are a few mums that hit on us,' Harry revealed this week.

His bandmate Louis added: 'Ask Harry - they just go for it. They will grab and pinch and it gets quite tricky.'

Alli moved to LA with her family two years ago and her older brother Cody has since hit the big time after being taken on by Justin Bieber's manager Scooter Braun.

'They grab and pinch': 1D have admitted to having to fight off the advances of much older women